Skimming mechanism for square tanks

ABSTRACT

A conventional skimming mechanism is carried by and between a track at the periphery of the tank and one arm of the sludge scraping and collecting structure which rotates about the center of the tank. The track is rectangular and provides the directional guidance of the mechanism. The arm moves the mechanism around the track through telescoping support means.

United States Patent 11 1 1111 3,77,132

Quast et a1. Nov. 6, W73

[54] SKIMMING MECHANISM FOR SQUARE 2,261,487 11/1941 Scott et al 2lO/529 TANKS 2,259,230 10/1941 Scott v 210/529 2,863,564 12/1958 Lind et al. 1 210/529 [75] Inventors: Gil r W- Q Brookfield; 2,238,024 4 1941 Linch 210 529 x Walter Poheim, Milwaukee; Ernest Schultz New Berlm of Primary ExaminerSamih N. Zaharna [73] Assignee: Rex Chainbelt Inc., Milwaukee, Wis Assistant ExaminerZ. A. Granger Filed Mar. 27 1972 Attorney-Ernst W. Schultz 21 A l. N 238 633 1 pp 0 57 ABSTRACT 52 vs. c1. 210/525 210/5 30 A conventicmal skimming mechanism is Carried by and 51 Int. Cl 1301a 21/00 between a track the PeFiPherY 0f the tank and one [58] Field of Search 210/525 528 529 am 0f the Sludge Scraping and Collecting Structure 6 which rotates about the center of the tank. The track is rectangular and provides the directional guidance of [56] References Cited the mechanism. The arm moves the mechanism around UNITED STATES PATENTS the track through telescoping support means.

2,611,489 9/1952 Scott 210/528 2 Claims, 5 Drawing Figures PATENTEDNUY s 1975 SHEET 1 [1F 2 :IIIIIIIIIIIIIIIIIII PATENIEDRUY ems 3770.132

SHEET 20F 2 I SKIMMING MECHANISM FOR SQUARE TANKS BACKGROUND OF THE INVENTION 1. Field of the Invention Tanks for the removal of suspended materials are generally circular and include a central rotating mechanism for the collection of the settled material. Rectangular tanks generally include reciprocating mechanisms. Both such tanks are readily provided with auxiliary skimming means.

A rotating collector mechansim for a square tank is shown in US. Pat. No. 2,863,564 and includes an outer extensible device which follows the generally square configuration of the tank. As in all square tanks hereinafter referred to, the corners of the tanks are rounded for mechanical reasons but this does not appreciably reduce the volumetric capacity of the tanks.

2. Background of the invention The skimming blade operates at right angles to and moves along the periphery of the tank. At a selected location, the blade pushes the scum up on a beach and into a trough extending between parallel baffles. Prior hereto, no suitable mechanism has been provided for the operation of such a skimming blade and especially one which forms an extension of a skimming blade which is supported by and rotates with the rotary sludge collector mechanism in a square tank.

SUMMARY OF THE INVENTION A first skimming blade extends from the center of the square tank and is carried by the rotary sludge collection mechanism. The second blade operates along the fixed scum baffle which extends around the tank and also pushes the scum up a beach and into a collection hopper. The two blades are functionally joined by a pivoting blade and by a blade which moves alongside the first blade. The second balde and the pivoting blade are carried in part and are guided by the track extending around the square tank to provide complete skimming of the square tank.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS FIG. I is a plan view of a square tank and includes separate plan views of the ends of the scraper arms to show their function.

FIG. 2 is a medial section of the tank shown in FIG.

FIG. 3 is an enlarged rear elevation of the skimming mechanism. The view is broken to show the support rollers which are carried by one arm of the scraper mechanism.

FIG.'4 is a plan view of the mechanism shown in FIG. 3.

FIG. 5 shows the beach and scum trough in cross section and the skimming mechanism operating thereover.

DESCRIPTION OF THE EMBODIMENT SHOWN IN THE DRAWINGS The tank It includes the square floor 12 and four side walls 13-16. The corners of the tank are filled to a radius which is in the order of one-third that of the circular sweep of the two arms 18 and 19 which are carried by the cage 20 of the rotary sludge collector mechanism. This allows the pivoted extensions 21 and 22 to follow suitable peripheral guide means and reach the entire settling area of the floor. The powered gear drive unit 24 is mounted on the center column 25 of the tank and supports the cage 20 and rotates the sludge collector mechanism which, as shown, is of conventional construction.

The inlet channel 28 includes wall 13 which is provided with a series of inlet ports 29; the similar effluent channel 30 includes the opposite wall 15 and is provided with a series of openings 31. Suitable weir means, not shown, maintains a substantially constant liquid level in the tank. This level is some distance below the upper edge of the plate 33 which extends around the tank with similar arcuate corner sections. Plate 33 is secured to the walls i3, 14 and 16 to form a wear strip for the scum pusher blade to be described and the portion of plate 33 extending along wall 15 is spaced therefrom to form a bafile which prevents the scum from being carried with the effluent through openings 31.

The arcuate baffle 35 is spaced from baffle 33 at the corner of tank 11 formed by walls 15 and I6 and therewith define the sides of the beach 36 which extends up to the edge of the scum receiving trough 38. The trough 38 which is provided with the scum discharge line 39 and the beach 36 are suitably fixed to and supported by the walls of the tank.

The scum pusher blade ll, referred to, includes a flexible seal-strip 411a and the forwardly extending arms 42a and b. This assembly is suspended from the wheeled carriage 43 which includes the horizontally projecting arm 44 having a support pivot 45 nearer its outer end. Carriage 43 includes support wheels 46 which ride on the track 47 and the lateral guidance wheels 48 and 49 which engage the sides of the track. Track 47 extends around the tank in a fixed or uniform relation to the plate 33 and is secured to the tank walls by suitable brackets.

The long, rigid control arm 51. for moving carriage 43 around the tank on track 47 has its outer end connected to the pivot 45 to support the outer end of arm 44 and is supported by and above the collector arm 18 by the rollers 52. For that purpose, the lower ends of upright columns 54 are fixed to arm 18 and carry the frame support 55 for the rollers 52 above the water level in the tank.

In the operation of the tank, the collector mechanism 20 is rotated on a regular schedule to move the settled sludge to the central collecting hopper, as shown. At the same time, the control arm 51 moves carriage 43 around the tank on track 47.

In particular, the scum collecting against the plate 33 where it forms a scum baffle alongside tank wall 15 is pushed by blade 41 in the direction of the beach 36. The scum collected between arms 42a and 42b is pushed up the beach and falls into the scum trough 38 each time the carriage moves around the corner at the location of the trough.

In many instances the collection of the scum may require sweeping the entire surface of the Water in the tank. For that purpose, the skimming blade 59 extends from the cage 20 to beneath the radially outer end of frame 55 and is supported by the collector arm 18 and the upright columns 57 and 54. The blade 61 which depends from control arm 51 is disposed immediately behind blade 59 and includes the portion 6ia which extends rearwardly (respecting its rotational movement about the center of tank ll) to the vertical shaft 641 which is rotatably held by the bracket 65 fixed to the control arm 51.

Bracket 65 is located so that the trailing end of the pivoting blade 67 fixed to shaft 64 is biased by the spring 68 to engage the arm 42b. Thus, as the collector arm 18 moves around the tank, the blades 59, 61, 67 and 41 provide complete skimming between cage 20 and plate 33.

Shaft 64 is, however, critically located some distance from arm 42b for two purposes. The relative movement of arms 44 and 51 about pivot 45 approaches 90 and spring 68 should maintain the trailing end of blade 67 in contact with arm 42 at all times except while the pusher blade 41 is operating between the parallel curved portion of plate 33 and the baffle 35. As the rotary skimming assembly approaches the beach 36, the pivoted blade 67 engages the end of baffle 35 which then pushes blade 67 away from arm 42b to the position shown in FIG. 4. This allows blade 41 to move normally up the beach 36 and over trough 38 and down the ramp 71. At the same time, spring 68 maintains the end of blade 67 in contact with baffle 35. When the end of 20 blade 67 reaches the end of baffle 35, the blade is again moved by spring 68 and shaft 64 into engagement with arm 42b.

We claim:

1. In a non-circular tank for containing a liquid with a constant liquid level and having an inlet, a peripheral outlet and sludge removal means which includes a collector arm extending over the floor of the tank and which rotates about a vertical axis at the center of the tank; a beach and scum trough fixed to and projecting from a wall of the tank, a track carried by the walls of the tank and extending around the tank, radially arranged guide means carried by the collector arm, a wheeled carriage operable on said track and a radial control arm movable lengthwise in said guide means, said carriage and arm being pivotally interconnected to form a support which follows the track around the tank while being rotated around the tank by the rotation of the sludge collector, an outer skimming blade carried by said support and disposed to follow the tank wall and operate over the trough and beach, an inner skimming blade carried directly by the sludge collector arm and extending radially from near the center of the tank, and an intermediate skimming blade carried by said control arm in telescopic relation with said inner blade and extending to the outer blade whereby the three blades provide skimming of the entire surface of the liquid in the tank.

2. The combination of claim 1 wherein the beach and scum trough includes a baffle generally parallel to and spaced from the wall of the tank and the radially outer end of the skimming blade carried by the control arm is pivotally movable by said-baffle to allow the same to pass the baffle as the outer blade moves up the beach and over the trough. 

1. In a non-circular tank for containing a liquid with a constant liquid level and having an inlet, a peripheral outlet and sludge removal means which includes a collector arm extending over the floor of the tank and which rotates about a vertical axis at the center of the tank; a beach and scum trough fixed to and projecting from a wall of the tank, a track carried by the walls of the tank and extending around the tank, radially arranged guide means carried by the collector arm, a wheeled carriage operable on said track and a radial control arm movable lengthwise in said guide means, said carriage and arm being pivotally interconnected to form a support which follows the track around the tank while being rotated around the tank by the rotation of the sludge collector, an outer skimming blade carried by said support and disposed to follow the tank wall and operate over the trough and beach, an inner skimming blade carried directly by the sludge collector arm and extending radially from near the center of the tank, and an intermediate skimming blade carried by said control arm in telescopic relation with said inner blade and extending to the outer blade whereby the three blades provide skimming of the entire surface of the liquid in the tank.
 2. The combination of claim 1 wherein the beach and scum trough includes a baffle generally parallel to and spaced from the wall of the tank and the radially outer end of the skimming blade carried by the control arm is pivotally movable by said baffle to allow the same to pass the baffle as the outer blade moves up the beach and over the trough. 